Chapter 1.4

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Vocabulary:

Ocean Ridge: the longest chain of mountains in the world
Sea-floor Spreading: the process that continually adds new material to the ocean floor.
Deep-ocean Trenches: the place where oceanic crust bends downward
Subduction: the process where the ocean floor sinks beneath a deep-ocean trench and back into the Mantle

Outline

Sea-Floor Spreading

• Mapping the Ocean Ridge
  • East Pacific is the longest chain of mountains in the world
  • Scientists map ridge with sonar
• Evidence for Sea-Floor Spreading
  • Harry Hess examined mid-ocean ridge
  • The continents DO move
  • The ocean floor moves like conveyer belt, creating new rock and swallowing the old
  • Process is called sea-floor spreading
  • Evidence From Molten Matieral
    • Alvin's crew found weird shaped rocks in mid-ocean ridge
  • Evidence From Magnetic Stripes
    • Magnectic poles reversed lots of times
    • Rock have same magnetic charge if cooled at the same time
  • Evidence From Drilling Samples
    • Scientists found that the farther the samples were taken from MOR(mid-ocean ridge), the older it is
• Subduction at Deep Ocean Trench
• Subduction and the Earth's Ocean
  • Subduction in the Pacific
    • Pacific Ocean is SHRINKING! because of too many trenches
    • Mid-ocean ridge cannot produce how many rock that has already been taken
  • Subduction in the Atlantic
    • Atlantic Ocean is expanding, because there aren't enough trenches to take up too much rock
    • Atlantic's oceanic crust pushes the continental crust